The purpose of this study is to determine the effect of dietary protein levels on lifespan of the hamster as related to the severity of nephritis. An attempt will also be made to correlate the degree of nephritis with hypertension. Weanling male and female golden Syrian hamsters will be fed either 6, 12, 18 or 24 percent protein in a pelleted ration. The mean lifespan of each group will be calculated and survivors will be killed when 20% of a group remains. All hamsters will be necropsied and the kidneys will be examined histologically for nephritis. Other major organs will also be examined for lesions. Prior to necropsy of survivors, blood pressure will be determined by cannulation of the carotid artery.